Extend or move: how much does an extension cost?

Read time: 7-8mins
By: Lucy Xu

When you purchase a home you don’t really consider your future requirements as much as your current circumstances.

You’re more focused on your budget, the home location, condition and design. At that point, most new homeowners don’t consider if they might need extra space in the future for children, elderly parents, other family members etc.

Eventually, they can be forced to squeeze into a smaller house, share bedrooms and bathrooms and generally feel uncomfortable. In such cases, there are two options – either move and purchase a bigger house or invest in a home extension.

There are advantages and disadvantages to both so you should consider the decision carefully.

Should you extend or move?

This decision is usually quite personal and depends on your particular circumstances. Some people find it more convenient to move into a new house, while others would rather not move. Here are some reasons why you should consider home extension:

1. You don’t have to move

Moving is a long, harrowing process that involves placing your current home on the market, looking for a new home, looking for financial assistance, making arrangements for school transfer, utility transfer, arranging for the physical move, etc.

The entire process can be quite stressful. You don’t need to endure so much trouble if you choose an extension because you won’t have to change your property. You can simply get financial assistance to add a new room and remodel your existing home.

2. You can modify your property according to your preferences

With a new home you’ll have to settle for the existing design and adjust accordingly. However, if you choose an extension, you can easily create a design that appeals to you personally and add it to your home.

For example, you can choose the size of the room, bathrooms, the design, the material and other such factors. You don’t need to settle for the closest match to your preferences.

3. It’s more affordable

In most cases, an extension is more affordable than a move, particularly when you take into account real estate fees and stamp duty. If you have equity on your home consider refinancing your mortgage to finance the extension.

You could tailor your extension according to your preferences and budget. You might get more value for money if you invest in extension and a remodel as well.

4. Personal attachment

Most homeowners are emotionally attached to their home and don’t want to move unless they have to. If you choose an extension, you won’t have to move and can easily modify your current home to suit your needs. There’s no need to force yourself to leave.

As you can see, an extension has several advantages. There are some advantages of moving as well, especially if you’re not particularly attached to your home or neighbourhood.

Costs for different types of home extension

Different types of home extension projects will have different costs. It’s a good idea to create a plan before you even approach a contractor for the job. The first thing you need to do is consider your requirements and the architecture of your existing property. For example, do you want to add another floor to your home?

Do you just want to convert your basement to a guest room? Do you want to add a room to your property? Do you want to build a room above the garage? The answers to these questions will help you determine what you need from the extension project. You can then consider the costs involved.

1. Single-storey extensions

Single story extensions can cost anywhere between $1,350 per m2 to $2,100 per m2. This cost depends largely on the type of materials you use and the design you choose.

According to Domain, the cost of adding an 80-square-metre ground-floor extension ranges from $164,526 to $310,896.

2. Two-storey extensions

If you want to add a two-storey extension, you’ll have to add 50% to the cost of the single story extension. For example, if the single story extension costs $2,100 per m2, you’ll need to add another $1,050 per m2 to reach an accurate price.

This project will cost around $3,150 to $3,200 per m2. This is a conservative estimate.

3. Loft conversion

Loft conversion can be a little pricy because you need to insulate the space, add a secure floor and carry out other such alterations to make the space liveable. In most cases, the loft conversion costs around $1,500 to $2,500 per m2 based on your requirements and the amount of work needed.

4. Build a conservatory

Conservatories have glass windows, roofs and other such attachments, which can add to the cost of the extension. You need to choose materials that will protect you from the Australian sun and ensure you have a comfortable space.

The cost of the conservatory depends largely on the materials used, but you can expect the total cost to be anywhere between $5,000 and $30,000. Conservatories have to be designed according to the surroundings so you need a detailed quote to get an accurate idea of the cost.

5. Basement conversion

Basement conversions, especially those that involve excavation can cost anywhere between $250,000 and $500,000 depending on the material, design and size. Contractors need to be extra careful and must try to protect the property above it as much as they can, which is why most basement conversions are pricey.

6. Garage conversion

Garage conversions can be affordable because the space already has a roof, four walls, solid floor and a foundation. You only need to make it more comfortable for it to serve as your living quarters.

Garage conversions can range from $7,500 to $20,000 and are more based on the extent of the modification and repairs. The more complex the design, the higher the price.

7. Cellar conversion

Cellar conversions can be just as expensive and complicated as basement conversions, which is why the prices for these projects can range between $250,000 and $500,000. If you already have cellar or basement space, you can exclude the cost of excavation and significantly reduce the price.

If you just need to make cosmetic changes to the cellar, you won’t need to spend more than $20,000 to $30,000 based on the design and materials used.

Bear in mind that all these building cost estimates are just averages. You’ll only understand your true cost burden if you get a personalised quote from a good contractor. This information is only to help you form a preliminary budget.

You should also consider a 10% buffer on your budget because unexpected expenses can surface. Add 10% to any final budget estimate you come up with and that will be your overall budget for the job.

Costs to consider

Regardless of the type of extension you are getting done there are certain common costs to consider. When you receive the estimate from a contractor it will be divided into several sections explaining different costs involved, which include:

1. Heating

Heating, cooling and insulation are essential to keep your new extended space comfortable. You’ll need to factor in the cost of the HVAC (Heating, ventilation and air conditioning) and insulation in every project because without them, the space can beunliveable.

2. Piping and gas extension

If you intend to have a bathroom or kitchen in the extended room, you may need to install gas and piping, depending on the type of energy you choose. The materials, planning, design and the installation cost will add to the overall expense of the extension.

If you just want to use electricity you should only require electrical wiring. Consult your local gas fitting experts or electricians to find a custom solution.

3. Material cost

The quality and quantity of the materials have an impact on the overall cost of the project. If you use special and expensive materials in the project, the cost will increase considerably.

The cost of using different materials like timber, flat pack and glass, will have an impact on the overall estimate. For example, a single floor extension with timber will cost around $1,500 to $2,100 per m2 while one with vinyl will cost around $1,350 per m2.

4. Planning and building cost

Planning and building requires a lot of effort and time. Designers and architects carefully consider all variables and create a floor plan. Once you approve of this plan, the contractors move on with the rest of the project.

This process usually involves:

Structure design – Where the designers finalise the design and make sure all measurements and scales are accurate. This design process is billed separately.

Builder – The actual construction work involves separate costs that include labour and time consumed.

Roofing and tiling – The newly extended area will need a solid roof and flooring. Roof installation is complicated and requires special expertise so it’s charged separately.

Interior finishing – If you want the new space to look pleasant, you need to finish it with drywall, paint, flooring, accessories, etc. You may need the expertise of an interior designer to ensure the finished room looks great and put-together. They’ll charge added fees for their services, which contributes to the cost.

The cost will also include expenses like building permit, insurance, taxes, etc. When you receive a quote, check to see if all expenses are included and that there are no hidden costs.

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